Using an air pressure gauge for tires is one of the easiest ways to save money on gas.  The largest enemy of gas mileage is friction.  Friction is mainly caused by three factors: brake usage, friction from the wind, and friction from the road.  There is not much you can do about the first two factors unless you happen to only drive on empty roads with a strong back wind.  However, a simple check of your tires can help squeeze the most out of every drop of gas you buy at the pump.

## How an Air Pressure Gauge Works

There are two main categories of air pressure gauges, pencil and digital, that work under the same principle.  Pressing the gauge against the nozzle causes air to release from the tire since pressure always attempts to equalize.  Pencil style gauges have a piston that the incoming air pushes against.  A spring is specifically designed to accurately measure how much air pressure is pushing against the piston and then displays the pressure on the indicator that pops out of the gauge.  The pounds per square inch (PSI) is the last marking you can see exiting the gauge.  Digital air pressure gauges follow the same concept except the spring is by a pressure reader that displays the PSI on a digital screen.

## How Do You Use an Air Pressure Gauge

Checking the pressure of your tires is doable by anyone regardless of their mechanical abilities.  The first step is to screw the cap off the nozzle on your tire.  The nozzle is typically black and cannot be mistaken for anything else.  Then you take your air pressure gauge and press the head against the open nozzle.  You will hear a hiss as a bit of air escapes which will be followed by your indicator popping out or your digital display showing your PSI.  Make note of the PSI number before screwing the cap back on the nozzle.  Repeat these steps till you have checked all your tires.

## What is the Correct Tire Pressure

Using an air pressure gauge for tires will only get you a number, but how you use that information will depend on your personal preference.  There are two main options for tire pressure: a more comfortable ride or a most fuel-efficient ride.  Your tires will have a max PSI listed on the side, but you should follow the PSI recommendation for your vehicle.  The general range is between the low 30's and 40.  The higher end of this range will give you better gas mileage but is not as smooth of a ride as the lower end of the scale.  Having a lower PSI allows the tire to absorb the roads bumps and debris at the cost of more friction on the road.  No one knows your driving conditions and needs better than you so the choice is yours.

## Which Gauge: Digital versus Pencil

Both types of air pressure gauge for tires work well.  The main advantage of a digital version is that it is self-lighting so you will certainly be able to correctly read the measurement.  However, since it is a powered device it also requires batteries.  The lack of batteries on the pencil model means that it will never run out of power.  If you pack a flashlight in your car as well, than reading the measurement in the dark is not an issue.  Keeping one in your car, regardless of the style you choose, will go a long way in keeping your car running how you want it.